Progressive Web App questions

March 15th, 2017

I got a nice email recently from Colin van Eenige. He wrote:

For my graduation project I’m researching the development of Progressive Web Apps and found your offline book called resilient web design. I was very impressed by the implementation of the website and it really was a nice experience.

I’m very interested in your vision on progressive web apps and what capabilities are waiting for us regarding offline content. Would it be fine if I’d send you some questions?

I said that would be fine, although I couldn’t promise a swift response. He sent me four questions. I finally got ‘round to sending my answers…

1. https://resilientwebdesign.com/ is an offline web book (progressive web app). What was the primary reason make it available like this (besides the other formats)?

Well, given the subject matter, it felt right that the canonical version of the book should be not just online, but made with the building blocks of the web. The other formats are all nice to have, but the HTML version feels (to me) like the “real” book.

Interestingly, it wasn’t too much trouble for people to generate other formats from the HTML (ePub, MOBI, PDF), whereas I think trying to go in the other direction would be trickier.

As for the offline part, that felt like a natural fit. I had already done that with a previous book of mine, HTML5 For Web Designers, which I put online a year or two after its print publication. In that case, I used AppCache for the offline functionality. AppCache is horrible, but this use case might be one of the few where it works well: a static book that’s never going to change. Cache invalidation is one of the worst parts of using AppCache so by not having any kinds of updates at all, I dodged that bullet.

But when it came time for Resilient Web Design, a service worker was definitely the right technology. Still, I’ve got AppCache in there as well for the browsers that don’t yet support service workers.

2. What effect you you think Progressive Web Apps will have on content consuming and do you think these will take over the purpose of some Native Apps?

The biggest effect that service workers could have is to change the expectations that people have about using the web, especially on mobile devices. Right now, people associate the web on mobile with long waits and horrible spammy overlays. Service workers can help solve that first part.

If people then start adding sites to their home screen, that will be a great sign that the web is really holding its own. But I don’t think we should get too optimistic about that: for a user, there’s no difference between a prompt on their screen saying “add to home screen” and a prompt on their screen saying “download our app”—they’re equally likely to be dismissed because we’ve trained people to dismiss anything that covers up the content they actually came for.

It’s entirely possible that websites could start taking over much of the functionality that previously was only possible in a native app. But I think that inertia and habit will keep people using native apps for quite some time.

The big exception is in markets where storage space on devices is in short supply. That’s where the decision to install a native app isn’t taken likely (given the choice between your family photos and an app, most people will reject the app). The web can truly shine here if we build lightweight, performant services.

Even in that situation, I’m still not sure how many people will end up adding those sites to their home screen (it might feel so similar to installing a native app that there may be some residual worry about storage space) but I don’t think that’s too much of a problem: if people get to a site via search or typing, that’s fine.

I worry that the messaging around “progressive web apps” is perhaps over-fetishising the home screen. I don’t think that’s the real battleground. The real battleground is in people’s heads; how they perceive the web and how they perceive native.

After all, if the average number of native apps installed in a month is zero, then that’s not exactly a hard target to match. :-)

3. What is your vision regarding Progressive Web Apps?

For me, progressive web apps don’t feel like a separate thing from making websites. I worry that the marketing of them might inflate expectations or confuse people. I like the idea that they’re simply websites that have taken their vitamins.

So my vision for progressive web apps is the same as my vision for the web: something that people use every day for all sorts of tasks.

I find it really discouraging that progressive web apps are becoming conflated with single page apps and the app shell model. Those architectural decisions have nothing to do with service workers, HTTPS, and manifest files. Yet I keep seeing the concepts used interchangeably. It would be a real shame if people chose not to use these great technologies just because they don’t classify what they’re building as an “app.”

If anything, it’s good ol’ fashioned content sites (newspapers, wikipedia, blogs, and yes, books) that can really benefit from the turbo boost of service worker+HTTPS+manifest.

I was at a conference recently where someone was given a talk encouraging people to build progressive web apps but discouraging people from doing it for their own personal sites. That’s a horrible, elitist attitude. I worry that this attitude is being codified in the term “progressive web app”.

4. What is the biggest learning you’ve had since working on Progressive Web Apps?

Well, like I said, I think that some people are focusing a bit too much on the home screen and not enough on the benefits that service workers can provide to just about any website.

My biggest learning is that these technologies aren’t for a specific subset of services, but can benefit just about anything that’s on the web. I mean, just using a service worker to explicitly cache static assets like CSS, JS, and some images is a no-brainer for almost any project.

So there you go—I’m very excited about the capabilities of these technologies, but very worried about how they’re being “sold”. I’m particularly nervous that in the rush to emulate native apps, we end up losing the very thing that makes the web so powerful: URLs.